Organic polymers each containing at least one reactive silyl group per molecule are known to have a characteristic that they are cross-linked by siloxane bond formation involving hydrolysis or other reactions of the silyl group due to factors. such as moisture even at room temperature, whereby rubbery cured products are obtained.
Among such reactive silyl group-containing organic polymers, those whose backbone skeleton is a polyoxyalkylene polymer or a polyisobutylene polymer have already been produced industrially and are widely used in applications such as sealing materials, adhesives and paints (Patent Literature 1, Patent Literature 2).
In addition, the reactive silyl group-containing organic polymers with high molecular weights have been used in order to achieve excellent tensile properties. It has been necessary for curable compositions containing a high molecular weight polymer to incorporate a plasticizer in order to ensure workability. Meanwhile, high hardness may also be required depending on the particular application, and improved compositions are thus desired.